These studies aim at reconstruction and detailed understanding of molecular events underlying microphysiological function at both normal and pathologically deranged synapses. Electrophysiological and ultrastructural investigations will be combined with supercomputer simulations employing novel Monte Carlo algorithms. At present, the focus is on the vertebrate neuromuscular junction and neuromuscular disease as a model system. In particular, experimental and simulation studies will address the biophysical factors critical to the generation of endplate currents at the normal junction, and the interplay of those factors in the pathogenesis and treatment of myasthenic syndromes. In the long run, methods and results obtained from these studies will be applied to other single and multi-synaptic systems in the peripheral and central nervous system. Present electrophysiological studies aim at determination of highly accurate endplate current data and single channel (acetylcholine receptor) data. Endplate current data will be obtained using highly optimized two electrode voltage clamp techniques. Single channel investigations will employ patch clamp and noise analysis techniques, which represent new training experience. Ultrastructural investigations will employ high voltage electron microscopic tomography for full scale three-dimensional reconstructions of junctional geometry. They will also employ quantitative electron microscopic autoradiography to determine synaptic densities of acetylcholinesterase in several preparations. The techniques to be employed in ultrastructural investigations also represent new training experience. All of the experimental information gained will serve as either input or test parameters for supercomputer simulations. Because of the use of Monte Carlo simulation algorithms, it will be possible to combine modeling of molecular acetylcholine diffusion, molecular interactions of acetylcholine with receptors and acetylcholinesterase, and full scale synaptic ultrastructure for the first time. This will yield important insights into synaptic function that were not previously obtainable.